Welding



Ju1y18,1944. G. H. PHELQS 2,354,173

WELDING Filed Aug. s,- 1941 INVENTOR,

'f4 OPA/EY Patented July1s,.1944

UNITED STATES PATENT OFFICE WELDING George H. Phelps, Floral Park, N. Y.Application August s, 1941, seria1N0.4o5,963

c claims. (ci. 21o- 10) The invention herein disclosed relates to 4elec--tric resistance welding, and more particularly to the welding of apiece of metal so formed that the weld area does not heat uniformly withthe passage of the welding current. y The sections of pieces to bewelded, at the wel area, are often such that there is a variation in theheating between portions of the edges to be welded. For example, thesection of the piecesv at the weld area may be irregular. In this casethere are greater areas in contact at certain portions of the edges thanat others. In consequence, there is a lesser resistance and slowerheating at such portions than at those portions having less area incontact. Again the edge or section of the pieces at the joint may besuch thatl part thereof is somewhat removed from the electrode. Suchpart is not subjected to as high a current density as other parts orportions and in consequence has a slower heating rate. Uneven heating inthe weld in this manner and for other similar causes is not conducive tothe production of uniform welds of high quality.

By the invention herein disclosed, uniform heating in electricresistance welding may be obtained in irregular and non-uniformsections. In accordance with the invention the lcontact-- ing edges ofthe pieces to be joined are formed to effect an irregular contact of theedges to be joined in accordance with the rate of heating of beaccomplished, for example, in the making of an article by electricresistance welding of two pieces together, by forming the pieces andthereafter swedging the edges of the pieces to vary separate portionsfrom what may be termed the plane of the edge. When the two pieces are'then brought together in the welding operation,

the contact between the edges to be joined is irregular andintermittent. The swedging is of course controlled to effect a contactbetween the edges in accordance with the normal rate of heating of theseparate portions in the weld area. In this way contact is first madeonly at those points having the slowest rate of heating. As the heatingcontinues the various portions come into contact, the portion having thehighest rate of heating coming into contact last. By properly separatingthe various portions oi the'edges, in this way, it is possible toachieve very uniform heating throughout the weld area and eifect auniform weld.

The invention while not limited to any particular article will be moreclearly understood from. the following description thereof as applied to.30 the various portions in the weld area. This may the making of amortar shell such as that illustrated in the accompanying drawing inwhich:

Fig. 1 is a plan of a longitudinally divided semi-shell sector;

Fig. 2 is a side elevation thereof;

Fig. 3 is an end elevation thereof; and

Fig. 4 is a side elevationA of two shell sectors in the welding dies orelectrodes of an electric resistance Welder.

In the making of parts that are to be joined together by electricresistance Welding, it is necessary to allow for the take-up as the weldis effected as the'metal at the edges of the pieces is forced into eachother and metal is extruded at the joint. The longitudinally dividedsemishell sector disclosed in Figs. l to 3 of the drawing is thusformed. This shell sector is stamped from rolled platehaving across-section cornparable to an edge section of the shell sector.

4Two longitudinally divided semi-shell sectors are placed in electrodeshaving recesses similar to dies in which the shell sectors are received.The sectors are then brought together in edge to edge relation underheavy pressure and a heavy current is caused to flow between thesectors. In this way the sectors in the weld area are brought to Weldingtemperature and the metal at, the edges is forced together and the weld.effected.

The shell sector illustrated includes a nose yor forward end portion Iof a certain wall thickness and a tapering intermediate` portion 2 atthe rear of the forward end portion. This tapering portion has a wallsection that gradually decreases in thickness to a. transverse planeindicated by the line 3, and from this plane rearwardly it is ofsubstantially uniform thickness. At the end of the tapering portion 2,there is a short, substantially cylindrical portion I which is separatedfrom the tapering portion by a transverse barrier 5.

The plane of the axis of the shell sector is indicated in Fig. 2 by thecenter line 8. A like line 'l indicates a plane parallel to the axis ofthe shell sector but spaced therefrom by onehalf of the welding take-up.In the following description this plane l is taken as a reference planeand referred to for the purpose of description as the basic height.Certain parts of the edges of the shell sector, as hereinafterexplained, extend beyondor above the basic height in accordance withtheir normal rate of heating.

vIn the stamping and drawing of the shell sector, the edges thereofmayat all points extend beyond or above the basic height by the amountthat those portions having the slowest normal After the shell sector isdrawn, it is swedged in swedging dies to vary the relation of separateportions or areas with respect to the basic height and in accordancewith the normal rate of heating of such portions. lThe term inaccordance with" is not intended to imply a proportional re lation asthe relation may be empirical and arbitrary but rather indicates arelation in respect to the normal rate of heating of portions of anirregular section such as to produce a uniform heating in 'the area ofthe weld.

By the swedging operation on the shell sector illustrated, the edgeportions 8 (Fig. l) of the forward end, terminating at lines are allowedto extend beyond the basic height by ifteen thousandths of an inch. Theportions E0 between the lines and lines il extend, beyond the basicheight by seven thousandths or an inch. The portions i2 between thelines il and lines i3 extend four thousandths of an inch above the basicheight and the remainder of the edges of the tapering portion 2 'to therear of the lines i3, and outer edge of the cylindrical portion 13 areat the basic height.

The barrier which does not come into direct Contact with the electrodeshas a differential rate of heating. As will be seen from Fig. Li, theelectrodes i8 and is are recessed in the nature of dies and eachreceives av shell sector. IThe engagement of the elctrodes with theshell sector is between the surface of the electrode and the outersurface of 'the shell sector. Because of this, the center of thebarrier, that is the portion along the axis has a slower normal rate ofheating than the edges and the rate of heating progressively increasestowards the edges. To the end of modifying the contact of the barrier inaccordance with this differential rate of heating, and the portion ofthe edge of the cylindrical extension indicated as radially inwardly ofthe lines it, this portion of the contact area is rnade to conform to anarc of a circle indicated by the extension line ii (Fig. 3), and in thisinstance of a radius of three inches. The center point or axial centerline of the barrier extends above the basic height by fteen thousandthsof an inch and tapers to the basic height at the edges.

Two such sectors, swedged in this manner, are placed in electrodes E8and i9 of an electric resistance welder and the edges brought togetheras illustrated in Fig. 4. As both semi-shell sectors have been swedgedin the same manner, each has an edge variation of one-half of thatrequired to secure a uniform heat throughout the weld area, in otherwords, the relation of the yrate of heating extend beyond the basicheight.

various edge portions given above with respect to the semi-shell sectordescribed is one-half of the separation required to secure uniformheating.

When the serni-shell sectors are thus rst brought together only theportions 8 and the centers of the semi-barriers 5 come into contact. Asthe welding current flows, these portions become heated and softened,and under the pressure exerted the several portions come into contactsuccessively in accordance with their disf tance from or extensionbeyond the basic height.

A uniform heating throughout the weld area is thus attained and auniform weld effected between the semi-shell sectors.

The invention has been described as it is applied in the production ofshells, the parts of which are stamped and drawn from plate. It ishowever equally applicable to the welding of any two pieces in which thesection in the weld area is such that, normally, uniform heating wouldnot be obtained, and it will be obvious that various changes may be madeby those skilled in the art in the details of the application of theinvention described above within the principle and scope of theinvention as expressed in the appended claims.

I'claim:

l. In the method or electric resistance welding two pieces of metalhaving edge portions of different thickness and of different distancesfrom a surface and wherein the pieces are pressed together in edge toedge contact, electrical contact is made with surface" of the pieces andan electric current is caused to flow through the contacting edges, thestep which consists in shaping the contacting edges of the pieces toeffect a progressive separation of the edges inversely as the thicknessof the edge portions and the distance from the surface with whichelectrical contact is made.

2. In the method of electric resistance welding two pieces of metalhaving edge portions of different thickness and of different distancesfrom a surface and wherein the pieces are pressed together in edge toedge contact, electrical contact is made with surfaces of the pieces andan electric current is caused to flow through the contacting edges, thestep which consists in shaping by swedging the contacting edges of thepieces to effect a progressive separation of the edges inversely as thethickness of the edge portions and the distances from the surface withwhich electrical contact is made.

GEORGE H. PHELPS.

